pia-am335x: enable i2c pinmux if needed

- make sure we use the correct pinmux for i2c1 when trying to read
  the expansion eeprom

Signed-off-by: Björn Krombholz <b.krombholz@pironex.de>
pia-am335x-sk: add SK board to boards.cfg

Signed-off-by: Björn Krombholz <b.krombholz@pironex.de>
pia-am335x-pm: add some pull-ups to pinmuxing

- low active NOR control lines and PMIC INT

Signed-off-by: Björn Krombholz <b.krombholz@pironex.de>
pia-am335x-sk: add default pinmux for piA-AM335x-SK

Signed-off-by: Björn Krombholz <b.krombholz@pironex.de>
pia-am335x: avoid dupliate code in mmc0 pinmux

- all boards use the same mux set for mmc0

Signed-off-by: Björn Krombholz <b.krombholz@pironex.de>
pia-am335x: rework board defines

- don't add a new define for every similar board
- We only really care about the board type to decide on the pin muxing
  for I2C1. For this it's ok to add a define per different CPU board.

Signed-off-by: Björn Krombholz <b.krombholz@pironex.de>
pia-am335x: fix eeprom init for pm

- on PM we want to write both eeproms in FIRSTSTART mode

Signed-off-by: Björn Krombholz <b.krombholz@pironex.de>
pia-am335x-sk: fix board detection output for PM baseboards board

Signed-off-by: Björn Krombholz <b.krombholz@pironex.de>